This invention relates to polyamide compositions; and more particularly, to polyamide compositions which are resistant to chlorofluorohydrocarbon permeation.
Polyamide resins, including polycaprolactam, known under the generic name nylon, are noted for a number of their properties such as hardness, high tensile strength, toughness, and rigidity, but not flexibility. To achieve flexibility, it has been common practice to add a myriad of plasticizers.
At the present time, it is known to use nitrile rubber-based compositions to make flexible, fluorcarbon permeation resistance articles, such as hose and tubing. Additionally, nitrile rubbers, which are butadiene acrylonitrile copolymers, are flexible, and known for gas permeation resistance and oil resistance. The nitrile component resists fluorocarbon permeation and yet provides a flexible polymeric matrix. However, it is desirable not only to have a composition that has flexibility, and resistance to permeation, but at the same time has higher use temperatures and better general physical properties than existing nitrile rubber tubing and hose.
The Vanderbilt Rubber Handbook, R. T. Vanderbilt (1978), reviews nitrile rubber at pp. 169-187. Although it is known to blend nitrile rubber with materials such as polyvinyl chloride, chlorosulfonated polyethylene, and EPDM (Vanderbilt pp. 175, 186), to achieve a final composition having a combination of properties, compositions containing nitrile rubbers are often difficult to process above about 149.degree. C. (300.degree. F.) (Vanderbilt, p. 183). U.S. Pat. Nos. 4,197,379; 4,508,867 and 4,619,962 also disclose blends of nitrile rubber and nylon.